Usually machine vision cameras (also meaning expensive) have high sensitivity for IR- much more than security cameras, and hence get you better detail as well as faster frame rates and lower latency, but they are not possible to use in Isadora, you would need to feed the image via syhpon or spout, or use other tracking software and send the data over OSC.

As for span, pretty much any camera you will be looking at will have a removable cmount lens so you can get pretty much whatever area you want, but remember as you get wider lenses you get more distortion (fish eye) and the coordinates will not exactly match up.

It depends how much detailed tracking you need(as Fred points out too).

I have used security cam with IR light(nightvision) with MXO2\. The latency was just few frames(out of 30fcp) almost instant. The security cams are getting obsolete so fast that it is possible to get a good one for very little money second hand. Look for TV-lines - the higher the number the better is the picture quality.

But I have done a setup with hacked(IR filter removed) Sony Eyecam PS3 as well where we illuminated the background with IR, so the subject become as a shadow. PS3 is USB camera with great quality and very little latency. Only problem is the length of USB cable(you need an active(powered) extenders going over 3m).

is there any actors to do that ? for matching the coordinate to the real world?

- where is the best place place to put the IR emitter ( i switch off the ir led of the camera and put a PC with red/blue gels exactly on top of the dancer to avoid shadow ) ? as everyone say to put it in the back os the stage ?

- i have no problem to track one or two dancer in the dark with the actors method of vjsculpture ( effect mixer and freeze) .

But the ir tracking system is attached to a processing patch witch interact with the coordinate of the dancer .

When i project a video on the top ( videoprojecteur is placed exactly the nearest the camera) i have some difficulty to cancel the video projection from the video feed to "eye" or "eyes ++" ...the eye actor seems to doesn't know what is the dancer and what is projection on the floor .

I notice that the floor is a white carpet.

Normally the video projection should not be seen by the ir camera ?

I didn't put a lee 73 filter to the camera , is this will help ?

is there a patch example to follow to cancel the video projection for not be seen by ir camera ?

you need to filter out visible light from entering the camera - this will prevent it from seeing the projected image. so yes - you need some kind of IR pass filter - either something from a security camera or floodlight - or a combination of dark lee filters. thats one reason to use IR. the other is so that you can track your dancer in the dark. a single lantern directly overhead, filtered to only emit IR light, will not be useful (unless you want to track the dancer's shadow) - you need contrast between dancer and floor. i use profiles on floorstands, shuttered off the floor, to create a white shape of the dancer against a black background. (un-illuminated floor)